1. Field of the Invention
The present invention relates to signal monitoring circuits used for checking and controlling apparatuses such as electronic devices, and particularly to a signal monitoring circuit that can monitor a plurality of signals by only employing a meter chip.
2. Description of Related Art
Generally, an electrical system can be wired so that various monitoring signals, such as voltage signals or current signals, are generated. The monitoring signals correspond to measurements of various critical functions of the electrical system, which are determined according to practical requirements.
Referring to FIG. 2, a conventional multi-channel signal monitoring circuit of an electrical system is shown. The signal monitoring circuit includes four sensors 50, four meter chips 60, and a micro control unit (MCU) 70. The sensors 50 are adapted for collecting four monitoring signals of the electrical system, and each sensor 50 generates a pair of corresponding differential signals. Each meter chip 60 is electrically connected to an output of a corresponding one of the sensors 50, and receives the differential signals generated by the corresponding one of the sensors 50. The meter chips 60 are electrically coupled to the MCU 70, and generate corresponding meter signals to the MCU 70, then the MCU 70 processes the meter signals using a preset program.
The above-mentioned signal monitoring circuit is capable of monitoring a plurality of signals by employing the plurality of meter chips 60. Each of the meter chips 60 connects one of the sensors 50 with the MCU 70. That is, the MCU can only process a signal generated from a sensor via a respective meter chip. As a result, the more sensors there are, the more meter chips are needed for transmitting the signals generated from the sensors. Thereby the monitoring circuit is complex and costly.
What is desired, therefore, is to provide a multi-channel signal monitoring circuit which can monitor a plurality of signals by only employing a single meter chip.